Hindfoot motion after isolated and combined arthrodeses: Measurements in anatomic specimens

Passive motions at the subtalar joint, talonavicular joint and calcaneocubo id joint were measured in eight ankle specimens, using an ultrasonic motion analysis system. Arthrodeses of the three joints were performed in all fea sible combinations and the resulting motion change at the unfused joints wa s determined. Motion at the subtalar joint was not significantly affected b y fusion of the calcaneocuboid joint, reduced to one quarter by fusion of t he talonavicular and calcaneocuboid joints (double arthrodesis) and almost completely eliminated with all other fusions. Motion at the talonavicular j oint was not significantly affected by calcaneocuboid fusion and reduced to approximately one third with the subtalar and the double arthrodesis. Moti on at the calcaneocuboid joint was not significantly reduced by subtalar fu sion but almost completely eliminated in all fusions involving the talonavi cular joint. It is concluded that the talonavicular joint is the key articu lation for hindfoot motion. Double arthrodesis preserved significant motion at the subtalar joint. Fusion of the calcaneocuboid joint had no significa nt influence on remaining hindfoot motion.